Means for separating particles from fluids



V A. GOETZ MEANS FOR SEPARATING PARTICLES FROM FLUIDS Jan. 22,

2 Sheets-Sheet 1 Filed Sept. 8, 1958 INVENTOR. flz EX/IIVDE/E GOA-"77 itrates This invention relates to means for separating particles and is acontinuation-in-part of my copending application Serial No. 603,677filed August 13, 1956, now abandoned, for Means and Method of SeparatingParticles from Fluids. Included in the objects of this invention are:

First, to provide a means for separating particles from fluids whereinthe fluid containing the particles to be separated is caused to flowsubstantially turbulence free in a channel under conditions wherein thefluid and the particles therein are subjected to centrifugal force for acontrolled period calculated to drive all or a selected proportion,quantity or type of particle toward a surface of the channel forremoval.

Second, to provide a means of this class wherein means defining ahelical channel having an inlet and an outlet at its axial ends iscaused to rotate at high velocities while the particle bearing fluid isfed therethrough at a controlled rate to establish a laminar flow whilesubjecting the fluid and its particles to the centrifugal forcegenerated by the high speed rotation of the channel defining means.

Third, to provide a means of this class wherein the outer peripheralwall of said channel defining means may be removable and be prepared toadsorb or otherwise retain the particles forced into contact therewithfor later study.

Fourth, to provide a means of this class wherein: a scavaging fluid ofgreater density than the fluid in which the particles are suspended maybe caused to flow among the outer peripheral wall of the rotatinghelical channel and receive the particles driven to the outer peripheralwall by centrifugal force.

With the above and other objects in view as will appear hereinafter,reference is directed to the accompanying drawings in which:

FIGURE 1 is a side elevational view of one form of apparatus forseparating particles from fluids wherein the apparatus is intended forlaboratory use.

FIGURE 2 is an enlarged fragmentary longitudinal sectional view thereoftaken through 22 of FIGURE 1.

FIGURE 3 is a transverse sectional view thereof taken thourgh 33 ofFIGURE 2, showing the entrance ends of the helical separation chambers.

FIGURE 4 is a transverse sectional view taken through 4-4 of FIGURE 2,showing the exit ends of the helical separation chambers.

FIGURE 5 is a developed view of a record sheet removed from theapparatus.

FXGURE 6 is a diagrammatical view representing a straightened length ofa separation chamber indicating the rates at which different masses moveto the collector surface.

FIGURE 7 is a fragmentary longitudinal sectional view of a modified formof apparatus wherein a scavaging fluid is introduced to effectcontinuous removal of particles driven to the walls of the separatorchamber.

Reference is first directed to FIGURES 1 through 6. The constructionhere illustrated is intended primarily as a laboratory instrument forthe study of particles contained in aerosols by causing the particles tobe deposited on a record sheet such as the record sheet shown in FIGURE5.

A suitable base 1 is provided on which is mounted a motor shell 2containing a high speed electric motor not shown. The motor shell iscylindrical and is provided at its upper end with a partition retentionring 3 which secures within the upper end of the motor shell a partition4. The retention ring 3 forms a mounting shoulder which receives thelower end of a cylindrical rotor shell 5 at the upper end of the rotorshell there being provided a bearing mounting ring 6.

A shaft 7 extends upwardly from the motor through the partition 4 and into the bearing mounting ring 6. The upper portion of the shaft 7 isenlarged as indicated by 8 and is journalled within a ball or rollerbearing 9 which is prefitted in a sleeve bearing 10 which in turn isjournalled within a sleeve bushing 11 loosely received within thebearing mounting ring 6. The upper end of the sleeve bushing is providedwith a flange 12.

The lower portion of the tubular extremity 8 receives a rotor core 13which is in the form of a cone frustum and provided with helical ribs14. In the construction illustrated, two such ribs are provided whichdefine therebetween a pair of helical separation chambers 15 extendingfrom the upper or smaller end of the cone to the lower or larger endthereof. The upper extremities of the chambers 15 are connected byradially extended inlet ports 16 with the interior of the tubularextremity 8 of the shaft 7.

The lower or larger end of the rotor core receives an annular basemember 17 having a depending skirt 18. The base member forms in part thelower shoulder of the separation chambers 15 at their lower extremities,and is provided with downwardly directed outlet passages 19 in which aremounted orifice bushings 20. The skirt 18 fits within but clears thewalls of an annular channel 21 formed in the partition 4. Below theskirt 18 the channel 21 forms an annular outlet chamber whichcommunicates with an outlet port 22.

The rotor core receives a conical shell 23, the inner surface of whichis adapted to rest on the peripheral portions of the ribs 14 so as toclose the separation chambers 15. Positioned between the shell 23 andthe ribs 14 is a record sheet 24. The shell 23 is connected at its upperor smaller end to a mounting ring 25 by means of a screw threadconnection 26. The mounting ring is in turn connected to the tubularportion 8 of the shaft 7 by a screw thread connection 27. The screwthread connection 26 permits axial adjustment of the shell. Supported onthe bearing mounting ring 6 is a supporting disc 28 in which is centeredan entrance tube 29 having means at its outer portion for connection toa hose or the like. The entrance tube fits freely within the core of thetubular extremity 8 and extends to the inlet ports 16. At this end theentrance tube is provided with a triangular plug 29a having concavesides to form three ports 30 communicating with the bore of the tube andopen radially to communicate with the inlet ports. The entrance tube 29remains fixed during the operation of the apparatus, therefore, it ispreferable to provide three lateral ports 30 communicating with the twoinlet ports 16 in order to minimize any siren effect.

A cover member 28a having a central aperture overlies the upper end ofthe rotor shell 5. I

Operation of the apparatus illustrated in FIGURES 1 through 6 is asfollows:

Prior to conducting a test the apparatus is assembled with a recordsheet 24 interposed between the shell 23 and rotor core 13. The outletport 22 is connected to an exhaust line which may be a vacuum pressureline or may be arranged for discharge of air at atmospheric pressure.

Air or other fiuid to be analyzed is introduced through the entan-cetube 29. The air or fluid and the particles entrained therein move downthe entrance tube 29, flow radially through the inlet ports 16 and thenproceed to flow helically through the separation chambers 15. The fluiddischarges through the orifice bushings 2d, annular channel 21 andoutlet port 22.

The rate of flow of the air or fluid is predetermined by the capacity ofthe orifice bushings 20. As these orifices are small, the rate of flowof air or fluid through the helical separation chambers is relativelyslow. In any case, the velocity of flow is such that laminar flowconditions are maintained. During the time interval between the entranceof a quantity of air or fluid in the inlet ports 16 and its dischargethrough the orifice bushings 2d the air or fluid and the particlescontained therein are subjected to centrifugal force by rotation of theshaft 7 and rotor comprising the rotor core 13 and shell 23. Thecentrifugal force exerted may be many times the force of gravity; forexample, ten thousand times greater than gravitational force. Due to thefact that the flow is laminar, the particles within the separationchamber behave much as if they were contained within a quiescent fluid,but due to the fact that their masses have been increased enormously,the rate at which they settle toward the radially outer surfaces of theseparation chamber and on to the record sheet 24 is much more rapid thanwould be the case if only gravitational force were involved.

With reference to FIGURE 6 which represents diagrammatically a developedview of one of the separation chambers and assuming that all of theparticles contained in the fluid are of equal mass and that theparticles are randomly distributed at the entrance end of the separationchamher, it follows that all of these particles will move withsubstantially equal velocity toward the outer peripheral wall or recordsheet so that the fluid above the line as indicated by A in FIGURE 3will be free of such particles. If the particles are of greater mass,the line of demarcation between the particle-laden and particle-freefluid will be represented by B or if the mass is still greater, by C.

Reference is now directed to FIGURE 7. In the construction hereillustrated the particles are not deposited so as to remain on asurface, but are forced toward the surface and then entrained in adenser fluid and discharged through a separate exit. The construction,however, may be in many respects similar to the construction of thefirst described apparatus. A mandrel 31 is provided on which is formedthe helical fin 32 defining an annular channel or chamber 33. The upperend of the mandrel is provided with a deflector flange 34 and is joinedor otherwise secured to a shaft 35. The mandrel fits within a cup-shapedshell 36 having a hollow stem 37 which for-ms an inlet passage 38. Thebottom end of the mandrel and confronting wall of the shell 6 form aradial entrance duct 39 communicating with the helical channel orchamber 33. The shell 36 is incased in a lower housing 40 and journalledtherein by means of a bearing 41. The lower housing may rest on a basestructure 42, having a fixed inlet passage 43 communicating with theinlet passage 3%. Extending upwardly from the inlet passage 43 is afixed entrance tube 5311 which fits freely within the passage 23 and isprovided with radial ports communicating with the duct 39. Suitablydisposed in the inlet passage 43 is a spray 44 which discharges awashing fluid in pre-determined proportions to the flow of the mainfluid.

The upper portion of the mandrel 31 is covered by an upper housing 45 inwhich is provided a bearing 46 to journal the shaft 35. Formed in theupper housing and surrounding the deflector flange 34 of the mandrel 31is an annular primary collector channel 47. The upper housing also formsan annular wall 48, the inner surface of which is a continuation of theinner wall of the shell 36. The axial upper extremities of the annularwall 48 constricts the primary channel to form an annular discharge slit49 communicating between the annular space defined by the annular wall48 and the mandrel 31 and the primary collector channel 47.

The upper extremity of the shell 36 is provided with a radiallyoutwardly directed lip 50 which forms with the s low axial extremity ofthe wall 4% a secondary discharge slit 51. Outwardly of the dischargeslit 51 the upper and lower housings may form complementarily asecondary collector channel 52. The primary and secondary collectorchannels 47 and 52 communicate with discharge lines 53 and 545- havingregulator valves 55 and 56 to permit regulation of the rate of flowthrough the helical separation channel or chamber 33.

Operation of the construction shown in FIGURE 7 is as follows:

A fluid to be cleaned of particles such as particleladen air isintroduced through the entrance tube 43a. Water or other scavaging fluidof suitable density is introduced through the spray nozzle 44. .ie wateror cleaning fluid is driven by centrifugal force to the inner wall ofthe shell 36 that is, the peripherally or radially outer wall of thehelical passage or chamber 33. The water or washing fluid forms acontinuous film which travels to the discharge slit 51.

The particles in the particle-laden fluid are subject to highcentrifugal forces and migrate toward the wall 36 of the shell and areentrapped in the washing fluid. The particle-laden washing fluid isdischarged through the secondary discharge slit into the secondarydischarge channel 52. The particle-free fluid passes to the maindischarge slit 49 and to the collector channel 47.

The size and shape of the helical channel may vary according to the typeof fluid intended to be cleaned of particles by the apparatus.

Reduction in the radial dimension of the passage reduces the number ofconvolutions or length of the channel. The greater the diameter of therotor comprising the mandrel and the shell, the lower the rotationalvelocity for the same centrifugal force.

The term, fluid, as herein used is intended to include a liquid as wellas a gas. Also while the scavaging medium is preferably a liquid, it isconceivable that it, too, might be a gas, particularly if it had aunique aflinity for the particle to be collected.

Also the term particle is not limited to solid particles but alsoincludes liquid particles, and may, of course, be inorganic or organicin character.

Two factors contributing to separation of the particles from the fluidare the magnitude of the centrifugal force exerted and the period duringwhich the centrifugal force is applied. Various geometricalconfigurations may be utilized depending on the volume of the fluid tobe treated, the character of the particles to be removed and whether ornot the separation must be complete or may be partial.

Thus, for example, a single pitch helical conduit provides a long pathwith a small axial dimension and therefore is most suitable for completeseparation of particles from a relatively small volume of fluid. That isa single pitch helical conduit may provide maximum length to provide amaximum period of exposure to the centrifugal force.

However, multiple pitch helical conduits may be pro vided to increasethe volumetric capacity. This, of course, requires proportionateincrease in axial length of the rotor to effect a separationcorresponding to a single helix rotor. Still further, the pitch of thepath or paths may be increased to infinity, that is, the paths may beaxial. Such construction becomes feasible where separation is easilyaffected or where partial separation is suificient.

The method of separation of particles Whether accomplished by theapparatus hereinbefore described or other apparatus consists essentiallyin:

(l) causing substantially turbulent free or laminar flow of aparticle-laden fluid in a confined conduit wherein the boundary layer ofthe fluid approaches zero velocity relative to the conduit wall;

(2) simultaneously subjecting the fluid to centrifugal force so thatparticles in the fluid are driven by centrifugal force through theboundary layer into contact with wall for collection at the wall or in ascavaging fluid coating the wall.

(3) producing a sufficiently high centrifugal force for a sustainedperiod of such duration that particles to be collected which areinitially adjacent the wall remote or opposite from the collecting wallmay be forced transversely of the fluid to the collecting wall.

Reference is directed to FIGURE 5. The stippled stripes represent theareas of the record sheet exposed to the separator channels 15, and thestippling represents the particles which have settled out. Theindividual particles are, of course, of much smaller magnitude, and mayrange from a small fraction of a micron a to several microns a.

Reference is made to the bearing structure which supports the upper end8 of the shaft 7. The sleeve 11 is loosely retained in the mounting ringso that it tends to center itself. Movement is dampened by a washer 11aheld by the supporting disc 28 which is secured by screws to the ring 6.Also a viscous material such as grease is interposed between the sleeve11 and ring 6.

The ring 10 is rotatable in the sleeve and their confronting surfacesmate accurately to provide a minimum spacing therebetween. No lubricantis provided in this space; instead reliance is made on the thin body ofair between these surfaces; that is, the ring 10 and sleeve 11 functionas an aerodynamic bearing. This bearing under the conditions of highspeed rotation develops far less friction than the so-calledanti-friction bearing 9. AS a consequence the bearing 9 normally doesnot function but rotates at a unit. The aerodynamic bearing is morefully described in my co-pending application Serial No. 785,280 filedJanuary 6, 1959 and now patent number 3,012,827.

Having thus described certain embodiments and applications of myinvention, I do not desire to be limited thereto, but intend to claimall novelty inherent in the appended claims.

I claim:

1. A means for separating particles from fluids comprising: a rotordefining a helical conduit extending essentially the length of saidrotor and centered about the longitudinal axis thereof, said conduithaving an inlet and an outlet at its opposite ends but being otherwiseclosed by radially inner and outer spaced walls and adjoining wallswhich are spaced axially of said rotor, said radially outer walldefining a straight line in the axial direction of the rotor and havingan axial dimension at least as great as the distance between the wallsof said conduit adjoining said radially outer wall, means forintroducing a particle-laden fluid into the inlet end of said conduit,means for discharging particle-free fluid from the outlet end and meansfor maintaining the flow of fluid through said conduit at a velocityadequate to provide a stream having laminar flow, said last-named meanscomprising an adjustable flow restricting member in said outlet end;means for rotating said rotor at high speed to cause said conduit torotate about the axis of said rotor, there being no relative velocitybetween said conduit and its radially outer wall, whereby said particlesare driven in free paths between the adjoining walls of said conduit tothe radially outer wall and out of said stream; and maens for collectingthe thus driven particles on said outer wall, said outer wall beingremovable without disturbing the particles collected thereon wherebysaid collected particles may be subsequently studied.

2. A means for separating solid particles from fluids as set forth inclaim 1, wherein: said rotor includes a separable inner core and outershell, the inner wall of said shell defining the radially outer wall ofsaid helical conduit; and said collecting means is a removable collectorsheet covering said radially outer wall.

3. A means for separating solid particles from fluids as set forth inclaim 1, wherein: said radially outer wall defines a conical surfaceincreasing in diameter toward said outlet.

4. A means for separating solid particles from fluids as set forth inclaim 1, wherein: said rotor includes a separable inner core and outershell having confronting surfaces defining a cone increasing in diametertoward said outlet; and said collector means is a removable sheet in theform of an axially slit cone covering and conforming to said radiallyouter Wall.

References Cited in the file of this patent UNITED STATES PATENTS631,680 Staahlgren Aug. 22, 1899 1,061,656 Black May 13, 1913 2,004,011Podbielniak June 4, 1935 2,043,313 Wells June 9, 1936 2,311,606Bannister Feb. 16, 1943 2,472,475 Hamilton June 7, 1949 2,616,619MacLeod Nov. 4, .1952 2,688,437 Monnet Sept. 7, 1954 2,730,299 KelseyJan. 10, 1956 FOREIGN PATENTS 66,267 France Mar. 26, 1956 (Addition toNo. 1,067,028)

1. A MEANS FOR SEPARATING PARTICLES FROM FLUIDS COMPRISING: A ROTORDEFINING A HELICAL CONDUIT EXTENDING ESSENTIALLY THE LENGTH OF SAIDROTOR AND CENTERED ABOUT THE LONGITUDINAL AXIS THEREOF, SAID CONDUITHAVING AN INLET AND AN OUTLET AT ITS OPPOSITE ENDS BUT BEING OTHERWISECLOSED BY RADIALLY INNER AND OUTER SPACED WALLS AND ADJOINING WALLSWHICH ARE SPACED AXIALLY OF SAID ROTOR, SAID RADIALLY OUTER WALLDEFINING A STRAIGHT LINE IN THE AXIL DIRECTION OF THE ROTOR AND HAVINGAN AXIAL DIMENSION AT LEAST AS GREAT AS THE DISTANCE BETWEEN THE WALLSOF SAID CONDUIT ADJOINING SAID RADIALLY OUTER WALL, MEANS FORINTRODUCING A PARTICLE-LADEN FLUID INTO THE INLET END OF SAID CONDUIT,MEANS FOR DISCHARGING PARTICLE-FREE FLUID FROM THE OUTLET END AND MEANSFOR MAINTAINING THE FLOW OF FLUID THROUGH SAID CONDUIT AT A VELOCITYADEQUATE TO PROVIDE A STREAM HAVING LAMINAR FLOW, SAID LAST-NAMED MEANSCOMPRISING AN ADJUSTABLE FLOW RESTRICTING MEMBER IN SAID OUTLET END;MEANS FOR ROTATING SAID ROTOR AT HIGH SPEED TO CAUSE SAID CONDUIT TOROTATE ABOUT THE AXIS OF SAID ROTOR, THERE BEING NO RELATIVE VELOCITYBETWEEN SAID CONDUIT AND ITS RADIALLY OUTER WALL, WHEREBY SAID PARTICLESARE DRIVEN IN FREE PATHS BETWEEN THE ADJOINING WALLS OF SAID CONDUIT TOTHE RADIALLY OUTER WALL AND OUT OF SAID STREAM; AND MEANS FOR COLLECTINGTHE THUS DRIVEN PARTICLES ON SAID OUTER WALL, SAID OUTER WALL BEINGREMOVABLE WITHOUT DISTURBING THE PARTICLES COLLECTED THEREON WHEREBYSAID COLLECTED PARTICLES MAY BE SUBSEQUENTLY STUDIED.